1. Field of the Invention
The present invention relates to a method of repairing a repair target portion of an object damaged by receiving impact or the like by bonding a pre-cured repairing material to the repair target portion, and a product repaired using the repairing material.
2. Description of the Related Art
An outer panel (skin) forming an outer surface of a fuselage or a wing of an aircraft requires to be repaired if the outer panel is damaged by a lightning strike or flying objects such as hailstones. In this repairing, a composite material formed of fiber reinforced plastics (FRP) or the like is used as a repairing material for covering a repair target portion.
Such a composite material is produced by a method of laminating fibers, which is formed in a sheet form, and impregnated with a liquid resin, and curing the resin by heating (wet lay-up), or a method of laminating a half-cured intermediate material (prepreg), and curing this material by heating. A repairing patch heated and cured in advance (precured patch) is also used as the composite material.
Using a precured patch attains such advantages of securing stable quality of repairing, and facilitating storage of repairing materials.
In the case of using a precured patch, as described in Japanese Patent Laid-Open No. 10-156633, the precured patch is disposed on a surface of a repair target, and an adhesive disposed between the repair target and the precured patch is cured by heating so as to bond the precured patch to the repair target.
An outer panel of an aircraft is required to have a high smoothness in order to minimize drag in flight. Hence, the precured patch used in repairing of the outer panel is required to have an enough out-of-plane stiffness to withstand deformation and buckling if a great load is applied during flight so that the precured patch does not become deformed in the out-of-plane direction.
The out-of-plane stiffness denotes difficulty in deformation in the out-of-plane direction, and even involves shearing rigidity in which bending stiffness is dominant.
The precured patch is pre-cured in a predetermined thickness so as to satisfy a desired out-of-plane stiffness. This means that the precured patch already has an out-of-plane stiffness required during using a repaired product before repairing, and thus it is difficult to curve the precured patch along the surface of the repair target.
Consequently, even if the difference in shape between the precured patch and the repair target is small, a gap is generated between the precured patch and the repair target, which makes it difficult to bond the precured patch to the repair target. If the precured patch is forcibly pushed and bonded to the repair target, such force that peels off the precured patch 15 from the repair target 17 acts on the circumference of the precured patch 15 after the adhesive is cured, as shown in FIG. 6 (indicated by arrows), which significantly deteriorates the bonding strength.
Based on the above problems, the present invention relates to a repair method using a precured repairing patch, and a repaired product obtained from repairing using the repairing patch, and an object of the present invention is to securely bond a repairing patch, where an out-of-plane stiffness is required, to a repair target.